Aromatic amidines as antiviral agents in animals

ABSTRACT

Novel [N,N-di(higher alkyl)aminomethyl]benzamidine and substituted compounds such as [N,N-di(higher alkyl)aminomethyl]-N-(2-propyl)-benzamidine and [N,N-di(higher alkyl)aminomethyl]-N-(p-hydroxyphenyphenyl)-benzamidine and their non-toxic acid addition salts are useful for combating viral infections in vertebrate animals.

CROSS REFERENCE TO RELATED APPLICATION

This application is a division of application Ser. No. 708,180 filed July 23, 1976 now U.S. Pat. No. 4,025,555.

BACKGROUND OF THE INVENTION

Virus infections which attack animals, including man, are normally contagious afflictions which are capable of causing great human suffering and economic loss. Unfortunately, the discovery of antiviral compounds is far more complicated and difficult than the discovery of antibacterial and antifungal agents. This is due, in part, to the close structural similarity of viruses and the structure of certain essential cellular components such as ribonucleic and deoxyribonucleic acids. Nevertheless, numerous non-viral "antiviral agents", i.e. substances "which can produce either a protective or therapeutic effect to the clear detectable advantage of the virus infected host, or any material that can significantly enhance antibody formation, improve antibody activity, improve non-specific resistance, speed convalescence or depress symptoms" [Herrman et al., Proc. Soc. Exptl. Biol. Med., 103, 625 (1960)], have been described in the literature. The list of reported antiviral agents includes, to name a few, interferon and synthetic materials such as amantadine hydrochloride, pyrimidines, biguanides, guanidine, pteridines and methisazone. Because of the rather narrow range of viral infections that can be treated by each of the antiviral agents commercially available at the present time, new synthetic antiviral agents are always welcomed as potentially valuable additions to the armamentarium of medical technology.

U.S. Pat. No. 3,906,044 discloses the antiviral activity of certain adamantyl amidine compounds of the formula: ##STR1## wherein n is 0 or 1, and Ad is adamantyl or bridgehead carbon atom-substituted alkyladamantyl. The antiviral activity of the compound N-[bis-phenyl-(2-methoxy-5-chloro-phenyl)-methyl]acetamidine is disclosed in British Patent No. 1,426,603.

SUMMARY OF THE INVENTION

It has now been found that certain novel benzamidine and N-substituted benzamidine compounds are capable of combating viral infections in vertebrate animals. The novel compounds of this invention have the formula ##STR2## and the non-toxic acid addition salts thereof wherein R₁ and R₂ are each alkyl of from twelve to twenty-four carbon atoms; and

R₃ is selected from the group consisting of hydrogen; alkyl of from one to six carbon atoms; alkenyl of from three to six carbon atoms; cycloalkyl of from three to eight carbon atoms; phenyl; phenylalkyl of from seven to nine carbon atoms; pyridyl; pyrimidyl; dimethlamino; ##STR3## --(CH₂)_(n) CH₂ OH, --(CH₂)_(n) SO₃ H, and --(CH₂)_(n) CF₃, wherein n is an integer of from one to six; and mono- and di-substituted phenyl wherein said substituents are selected from the group consisting of fluoro, chloro, bromo, hydroxyl, nitro, trifluoromethyl, alkyl and alkoxy of from one to three carbon atoms, dimethylamino, --N(CH₃)₃ ⁺ Cl⁻, --SO₂ NH₂, ##STR4## wherein R₄ is alkyl of from one to three carbon atoms, provided that when said phenyl ring is di-substituted at least one of said substituents is selected from the group consisting of hydroxyl, alkyl and alkoxy of from one to three carbon atoms, and dimethylamino.

The invention disclosed herein comprises the novel antiviral compounds of formula I and the novel method of treating viral infections in vertebrate animals characterized by administration of a pharmaceutical composition containing an antivirally effective amount of a compound of formula I as the essential active ingredient.

DETAILED DESCRIPTION OF THE INVENTION

The compounds of formula I exhibit prophylactic antiviral activity in vivo in vertebrate animals. It is probable that these compounds function as antiviral agents by virtue of their ability to induce the production of endogenous interferon, although the present invention is not to be construed as limited by such a theory.

By "non-toxic" acid addition salts is meant those salts which are non-toxic at the dosages administered. The non-toxic acid addition salts which may be employed include such water-soluble and water-insoluble salts as the hydrochloride, dihydrochloride, hydrobromide, phosphate, diphosphate, nitrate, sulfate, acetate, hexafluorophosphate, citrate, gluconate, benzoate, propionate, butyrate, sulfosalicylate, maleate, laurate, malate, fumarate, succinate, oxalate, tartrate, amsonate (4,4'-diaminostilbene-2,2'-disulfonate), pamoate (1,1'-methylene-bis-2-hydroxy-3-naphthoate), stearate, 3-hydroxy-2-naphthoate, p-toluenesulfonate, methanesulfonate, lactate, dilactate, and suramin salts.

One preferred group of the compounds of formula I consists of the hydrochloride, dihydrochloride, hydrobromide, dihydrobromide, phosphate, diphosphate, lactate, methanesulfonate and succinate salts of the bases of formula I.

Another preferred group of the compounds of formula I consists of those wherein R₁ and R₂ are both normal alkyl.

Another preferred group of the compounds of formula I consists of those wherein R₁ and R₂ are both normal alkyl and contain the same number of carbon atoms.

Another preferred group of the compounds of formula I consists of those wherein R₁ and R₂ are both n-hexadecyl.

Another preferred group of the compounds of formula I consists of those wherein R₁ and R₂ are both n-octadecyl.

Another preferred group of the compounds of formula I consists of those wherein the benzene ring of said formula is meta-substituted.

The preferred substituents for R₃ are hydrogen; alkyl of from one to three carbon atoms; allyl; phenylalkyl of from seven to nine carbon atoms; dimethylamino; ##STR5## --(CH₂)_(n) --SO₃ H and --(CH₂)_(n) CF₃, wherein n is an integer of from one to three; and para-mono-substituted phenyl, wherein said substituent is selected from the group consisting of hydroxyl, methyl, methoxy, dimethylamino, --N(CH₃)₃ ⁺ Cl⁻ and --SO₂ NH₂.

Particularly valuable are the following compounds:

m-[N,N-di(n-hexadecyl)aminomethyl]-benzamidine,

m-[N,N-di(n-hexadecyl)aminomethyl]-N-(2-propyl)benzamidine,

m-[N,N-di(n-hexadecyl)aminomethyl]-N-(2,2,2-trifluoroethyl) -benzamidine,

m-[N,N-di(n-hexadecyl)aminomethyl]-N-allyl-benzamidine,

m-[N,N-di(n-hexadecyl)aminomethyl]-N-dimethylamino-benzamidine,

m-[N,N-di(n-hexadecyl)aminomethyl]-N-(p-hydroxyphenyl)-benzamidine,

m-[N,N-di(n-hexadecyl)aminomethyl]-N-(p-methoxyphenyl)-benzamidine,

m-[N,N-di(n-hexadecyl)aminomethyl]-N-methyl-benzamidine,

m-[N,N-di(n-hexadecyl)aminomethyl]-N-(p-dimethylaminophenyl)-benzamidine, and their non-toxic acid addition salts.

The compounds of this invention are prepared by methods familiar to those skilled in the art. The first step is generally the condensation of the appropriate α-[N,N-di(higher alkyl)amino]-toluonitrile with ethanthiol or ethanol in a hydrogen chloride saturated inert solvent such as chloroform to form the corresponding ethylthio-benzimidate or ethylbenzimidate dihydrochloride, as for example: ##STR6##

The second step is the reaction of H₂ NR₃ with the imidate. When R₃ is not hydrogen and H₂ NR₃ is not strongly basic, the second step of the preparation is the standard Pinner synthesis of amidines from imidates (Patai, S., ed., "The Chemistry of Amidines and Imidates", John Wiley and Sons, Inc., New York, 1975, pp. 283-341), i.e., the nucleophilic substitution of --NHR₃ for ethanthiol or ethanol in an inert solvent, e.g. chloroform, as for example: ##STR7## The reaction product is the desired N-substituted benzamidine.

When R₃ is not hydrogen and H₂ NR₃ is strongly basic, use of the standard synthesis described above yields the nitrile rather than the amidine. Efficient production of the amidine can be achieved, however, by pH control in the region 4-9 as e.g., with acetic acid or an acetic acid/sodium acetate buffer system as described in Examples 20-33.

Compounds of formula I wherein R₃ is hydrogen are prepared by condensation of the appropriate α-[N,N-di(higher alkyl)amino]toluonitrile with ethanol or ethanethiol in a hydrogen chloride saturated inert solvent such as dioxane to form the corresponding ethylbenzimidate or ethylthiobenzimidate dihydrochloride, followed by nucleophilic substitution with NH₃ and elimination of ethanol or ethanethiol, which is carried out in ammonia saturated ethanol. The reaction product is the desired [N,N-di(higher alkyl)aminomethyl]benzamidine.

The compounds wherein R₃ is --(CH₂)_(n) SO₃ H, wherein n is an integer of from one to six, are prepared by condensation of the appropriate [N,N-di(higher alkyl)aminomethyl]benzamidine (i.e. R₃ ═ H) with the appropriate γ-sultone or the appropriate sulfonic acid in an inert solvent, e.g. 1,2-dichloroethane. The compounds wherein R₃ is ##STR8## are prepared in the same manner using oxalyl chloride and the appropriate benzamidine.

It is to be understood that any reaction-inert solvent may be used in place of chloroform, dioxane or 1,2-dichloroethane in any of the methods of preparation described above. The list of acceptable reaction solvents includes, but is not limited to, chloroform, dioxane, 1,2-dichloroethane, ethyl acetate and methylene chloride. Each of the reactions described above is typically performed at or near room temperature.

It is to be understood that any of the common procedures for amidine synthesis referred to in the literature reviews, such as Patai, S., ed., op. cit., arising from the appropriate intermediates such as imidates, thioimidates, iminoyl chlorides, thioamides, nitriles, amides or amidines, may be used to produce the compounds of this invention.

Acid addition salts of the bases of formula I may be prepared by conventional procedures such as by mixing the amidine compound in a suitable solvent with the required acid and recovering the salt by evaporation or by precipitation upon adding a non-solvent for the salt. Hydrochloride salts may readily be prepared by passing dry hydrogen chloride through a solution of the amidine compound in an organic solvent.

The α-[N,N-di(higher alkyl)amino]-toluonitriles used as starting materials may be prepared by contacting α-bromo-toluonitrile with an appropriate N,N-di(higher alkyl)amine in dimethylacetamide in the presence of potassium carbonate. α-Bromotoluonitrile is an article of commerce obtainable, for example, from Shawnee Chemicals. The N,N-di(higher alkyl)amine is obtained by refluxing a (higher alkyl)amine with the appropriate carboxylic acid in a suitable solvent such as xylene and then contacting the N-(higher alkyl)amine which is formed with sodium bis-(2-methoxyethoxy)-aluminum hydride in a suitable solvent such as benzene to produce the desired N,N-di(higher alkyl)amine. Sodium bis-(2-methoxy-ethoxy)aluminum hydride is an article of commerce obtainable, for example from Eastman Kodak Corporation as a 70% solution in benzene under the trade name of Vitride. As will easily be recognized by those skilled in the art, this procedure may be employed to prepare N,N-di(higher alkyl)amines in which the alkyl groups are either identical or different. If an N,N-di(higher alkyl)amine with identical alkyl groups is desired, a process comprising refluxing the mono-(higher alkyl)-amine in a suitable solvent such as toluene in the presence of Raney nickel catalyst to produce the desired N,N-di(higher alkyl)-amine may also be employed. This latter process is not in common use because tertiary amines, which are typically difficult to separate from the desired secondary amine product, are frequently formed. This problem is not serious, however, when the alkyl groups are higher alkyl (i.e., twelve to twenty-four carbon atoms), because of the apparent steric hindrance to tertiary amine formation afforded by the great bulk of the alkyl moieties and the ease of separating tertiary from secondary (higher alkyl)amines.

The antiviral activity of the compounds of formula I is determined by the following procedure. The test compound is administered to mice by the intraperitoneal route eighteen to twenty-four hours prior to challenging them with a lethal dose of encephalomyocarditis (EMC) virus. The survival rate is determined ten days after challenge and an ED₅₀ [dosage level (mg of compound/kg body weight) required to obtain a fifty percent survival rate] calculated. The procedure in which the drug is given eighteen to twenty-four hours before, and at a distinctly different site from, virus injection is designed to eliminate local effects between drug and virus and identify only those compounds which produce a systemic antiviral response.

Certain of the compounds of formula I were also tested for their ability to induce circulating interferon in mice after parenteral administration, using the procedure described by Hoffman, W. W. et al., Antimicrobial Agents and Chemotherapy, 3, 498-501 (1973).

Parenteral, topical and intranasal administration of the above-described amidines to an animal before exposure of the animal to an infectious virus provide rapid resistance to the virus. Such administration is effective when given as much as five days prior to exposure to the virus. Preferably, however, administration should take place from about three days to about one day before exposure to the virus, although this will vary somewhat with the particular animal species and the particular infectious virus.

When administered parenterally (subcutaneously, intramuscularly, intraperitoneally) the materials of this invention are used at a level of from about 1 mg./kg. of body weight to about 250 mg./kg. body weight. The favored range is from about 5 mg./kg. to about 100 mg./kg. of body weight, and the preferred range from about 5 mg. to about 50 mg./kg. of body weight. The dosage, of course, is dependent upon the animal being treated and the particular amidine compound involved and is to be determined by the individual responsible for its administration. Generally, small doses will be administered initially with gradual increase in dosage until the optimal dosage level is determined for the particular subject under treatment.

Vehicles suitable for parenteral injection may be either aqueous such as water, isotonic saline, isotonic dextrose, Ringer's solution, or non-aqueous such as fatty oils of vegetable origin (cottonseed, peanut oil, corn, sesame) and other non-aqueous vehicles which will not interfere with the efficacy of the preparation and are non-toxic in the volume or proportion used (glycerol, ethanol, propylene glycol, sorbitol). Additionally, compositions suitable for extemporaneous preparation of solutions prior to administration may advantageously be made. Such compositions may include liquid diluents, for example, propylene glycol, diethyl carbonate, glycerol, sorbitol.

When the materials of this invention are administered, they are most easily and economically used in a dispersed form in an acceptable carrier. When it is said that this material is dispersed, it means that the particles may be molecular in size and held in true solution in a suitable solvent or that the particles may be colloidal in size and dispersed through a liquid phase in the form of a suspension or an emulsion. The term "dispersed" also means that the particles may be mixed with and spread throughout a solid carrier so that the mixture is in the form of a powder or dust. This term is also meant to encompass mixtures which are suitable for use as sprays, including solutions, suspensions or emulsions of the agents of this invention.

In practicing the intranasal route of administration of this invention any practical method can be used to contact the antiviral agent with the respiratory tract of the animal. Effective methods include administration of the agent by intranasal or nasopharyngeal drops and by inhalation as delivered by a nebulizer or an aerosol. Such methods of administration are of practical importance because they provide an easy, safe and efficient method of practicing this invention. For intranasal administration of the agent, usually in an acceptable carrier, a concentration of agent between 1.0 mg./ml. and 100 mg./ml. is satisfactory. Concentrations in the range of about 30 to 50 mg./ml. allow administration of a convenient volume of material.

For topical application the antiviral agents are most conveniently used in an acceptable carrier to permit ease and control of application and better absorption. Here also concentrations in the range of from about 1.0 mg./ml. to about 250 mg./ml. are satisfactory. In general, in the above two methods of administration a dose within the range of about 1.0 mg./kg. to about 250 mg./kg. of body weight and, preferably, from about 5.0 mg./kg. to about 50 mg./kg. of body weight will be administered.

The compounds employed in this invention may be employed alone, i.e., without other medicinals, as mixtures of more than one of the herein-described compounds, or in combination with other medicinal agents, such as analgesics, anesthetics, antiseptics, decongestants, antibiotics, vaccines, buffering agents and inorganic salts, to afford desirable pharmacological properties. Further, they may be administered in combination with hyaluronidase to avoid or, at least, to minimize local irritation and to increase the rate of absorption of the compound. Hyaluronidase levels of at least about 150 (U.S.P.) units are effective in this respect although higher or lower levels can, of course, be used.

Those materials of this invention which are water-insoluble, including those which are of low and/or difficult solubility in water, are, for optimum results, administered in formulations, e.g., suspensions, emulsions, which permit formation of particle sizes of less than about 20μ. The particle sizes of the formulations influence their biological activity apparently through better absorption of the active materials. In formulating these materials various surface active agents and protective colloids are used. Suitable surface active agents are the partial esters of common fatty acids, such as lauric, oleic, stearic, with hexitol anhydrides derived from sorbitol, and the polyoxyethylene derivatives of such ester products. Such products are sold under the trademarks "Spans" and "Tweens," respectively, and are available from ICI United States Inc., Wilmington Del. Cellulose ethers, especially cellulose methyl ether (Methocel, available from the Dow Chemical Co., Midland, Mich.) are highly efficient as protective colloids for use in emulsions containing the materials of this invention.

The water-soluble materials described herein are administered for optimum results in aqueous solution. Typically they are administered in phosphate buffered saline. The water-insoluble compounds are administered in formulations of the type described above or in various other formulations as previously noted. Dimethylsulfoxide serves as a suitable vehicle for water-insoluble compounds. A representative formulation for such compounds comprises formulating 25 to 100 mg. of the chosen drug as an emulsion by melting and mixing with equal parts of polysorbate 80 and glycerin to which hot (80° C.) water is added under vigorous mixing. Sodium chloride is added in a concentrated solution to a final concentration of 0.14 M and sodium phosphate, pH 7, is added to a final concentration of 0.01 M to give, for example, the following representative composition.

    ______________________________________                                                                 mg./ml.                                                ______________________________________                                         Drug                      50.0                                                 Polysorbate 80            50.0                                                 Glycerin                  50.0                                                 Sodium Phosphate Monobasic Hydrous                                                                       1.4                                                  Sodium Chloride           7.9                                                  Water                     842.0                                                                          1001.3                                               ______________________________________                                    

In certain instances, as where clumping of the drug particles occurs, sonication is employed to provide a homogeneous system.

The following examples illustrate the invention but are not to be construed as limiting the same.

EXAMPLE 1 Ethyl-m-[N,N-di(n-hexadecyl)aminomethyl]-benzimidate Dihydrochloride

A mixture of α-[N,N-di(n-hexadecyl)amino]-m-toluonitrile (29.0 g., 0.05 mole), ethanol (40 ml., 0.67 mole) and dioxane (100 ml.) was saturated with dry hydrogen chloride gas for 40 minutes at 15°-25° C. It was then stoppered and held overnight at room temperature. Thin layer chromatography analysis (4:1, benzene:ethanol on silica gel) indicated complete reaction of the nitrile. The mixture was evaporated in vacuo yielding the named product quantitatively as a foam [35.0 g., ˜ 100% yield, R_(f) .87 (4:1, benzene: ethanol on silica gel)].

EXAMPLE 2 m-[N,N-Di-(n-hexadecyl)aminomethyl]-benzamidine

Ethyl-m-[N,N-di(n-hexadecyl)aminomethyl]-benzimidate dihydrochloride (35.0 g., 0.05 mole) was dissolved in ethanol (150 ml.) and the mixture saturated with ammonia gas at 20° C. The mixture was held for three hours at 20° C., resaturated with ammonia gas at 20° C., and then stoppered and held overnight at room temperature. The mixture was evaporated in vacuo to a solid which was triturated with acetone (200 ml.), filtered, washed with water (4 × 100 ml.), triturated again with acetone (2 × 100 ml.), filtered and dried in vacuo overnight [22.0 g., 74% yield, R_(f) 0.42 (4:1, benzene:ethanol on silicic acid)]. The crude product was recrystallized from hot acetone (20.9 g., 70% yield, m.p.-forms a gel at 84° C.).

EXAMPLE 3 m-[N,N-Di(n-hexadecyl)aminomethyl]-N-(n-propane)sulfonic acid-benzamidine

m-[N,N-Di(n-hexadecyl)aminomethyl]-benzamidine (1.196 g., 2.0 mmoles) was added to a solution of 3-hydroxy-1-propanesulfonic acid-γ-sultone (244 mg., 2.0 mmoles) dissolved in 1,2-dichloroethane (15 ml.). The mixture was held for 18 hours at room temperature. It was then diluted to 300 ml. with ethyl acetate-ether (2:1), washed with 1N HCl (3 × 50 ml.), washed with saturated aqueous sodium chloride solution (3 × 50 ml.), dried (Na₂ SO₄) and evaporated in vacuo to an oil. The oil was crystallized from 1,2-dimethoxyethane/acetonitrile [531 mg., 35% yield, R_(f) 0.35 (4:1, benzene:ethanol on silicic acid), m.p.-forms a gel at 87°-95° C.].

EXAMPLE 4 m-[N,N-Di(n-hexadecyl)aminomethyl]-N-oxoacetic acid-benzamidine

In like manner to that described in Example 3 the compound m-]N,N-di-(n-hexadecyl)aminomethyl]-N-oxoacetic acid-benzamidine was prepared by using oxalyl chloride as starting material and a reaction time of 1.5 hours. The oil was crystallized from 1,2-dimethoxyethane [34% yield, R_(f) 0.31 (4:1, benzene:ethanol on silicic acid), m.p.-forms a gel at 97°-105° C.].

EXAMPLE 5 Ethyl-m-[N,N-di(n-hexadecyl)aminomethyl]-thiobenzimidate Dihydrochloride

A mixture of α-[N,N-di(n-hexadecyl)amino]-m-toluonitrile (23.2 g., 0.04 mole), ethanthiol (6.0 ml., 0.08 mole) and chloroform (100 ml.) was saturated with dry hydrogen chloride for 30 minutes at 20°-25° C. It was then stoppered and held for six days at 5° C. The mixture was evaporated in vacuo to a foam which was crystallized by trituration with 1,2-dimethoxyethane. The crude product was recrystallized from hot 1,2-dimethoxyethane/chloroform [24.9 g., 88% yield, R_(f) 0.79 (4:1, benzene:ethanol on silicic acid), m.p. 109°-111° C.].

EXAMPLE 6 m-[N,N-Di(n-hexadecyl)aminomethyl]-N-(p-methoxyphenyl)-benzamidine

A mixture of ethyl-m-[N,N-di(n-hexadecyl)aminomethyl]-thiobenzimidate dihydrochloride (1.074 g., 1.5 mmoles), p-anisidine (369 mg., 3.0 mmoles) and chloroform (10 ml.) was held at room temperature for sixteen hours. It was then diluted to 400 ml. with chloroform, washed with 1N HCl (2 × 50 ml.), dried (Na₂ SO₄) and evaporated in vacuo to a foam. The foam was crystallized from 1,2-dimethoxyethane [868 mg., 73% yield, R_(f) 0.64 (4:1, benzene:ethanol on silicic acid), m.p.-forms a gel at 84°-86° C.].

EXAMPLES 7-19

In like manner to that described in Example 6 the following compounds were prepared by using appropriate reactants (H₂ N-R₃) in place of p-anisidine: ##STR9##

    __________________________________________________________________________     Example           Reaction   Crystallization                                   Number                                                                              R.sub.3      Time (hrs.)                                                                          Yield (%)                                                                           Solvent System.sup.a                                                                    M.P. (°C)                                                                    R.sub.f.sup.b                       __________________________________________________________________________                       16    88   DME      86-88.sup.d                                                                         .50                                 8                                                                                    ##STR10##   16    88   DME      135-137                                                                             .47                                 9                                                                                    ##STR11##   16    73   DME      164-167                                                                             .69                                 10                                                                                   ##STR12##   16    67   DME      156-157                                                                             .73                                 11                                                                                   ##STR13##   48    19   DME/CH.sub.3 CN                                                                         85-87.sup.d                                                                         .83                                 12                                                                                   ##STR14##   48    59   DME/CHCl.sub.3                                                                          125.sup.d                                                                           .24                                 13                                                                                   ##STR15##   48    62   DME      152-154                                                                             .76                                 14                                                                                   ##STR16##   3     83   DME      167  .37                                 15                                                                                   ##STR17##   48    68   DME      91-92.sup.d                                                                         .69                                 16                                                                                   ##STR18##   48    89   DME/CHCl.sub.3                                                                          164.sup.d                                                                           .78                                 17                                                                                   ##STR19##   36.sup.c                                                                             8    DME      128.sup.d                                                                           .70                                 18                                                                                   ##STR20##   0.5   90   DME      167-169                                                                             .55                                 19                                                                                   ##STR21##   48    15   Acetone  75.sup.d                                                                            .69                                 __________________________________________________________________________      .sup.a DME.tbd.1,2-dimethoxyethane; CH.sub.3 CN.tbd.acetonitrile;              CHCl.sub.3 .tbd.chloroform                                                     .sup.b 4:1, benzene:ethanol on silicic acid                                    .sup.c reaction carried out at reflux                                          .sup.d forms a gel                                                       

EXAMPLE 20 m-[N,N-Di(n-hexadecyl)aminomethyl]-N-cyclopentyl-benzamidine

Ethyl-m-[N,N-di(n-hexadecyl)aminomethyl]-thiobenzimidate dihydrochloride (1.074 g., 1.5 mmoles) was added to a solution of cyclopentylamine (255 mg., 3.0 mmoles), glacial acetic acid (0.3 ml., 5.3 mmoles) and chloroform (10 ml.). The mixture was held for 72 hours at room temperature. It was then diluted to 300 ml. with chloroform, washed with saturated aqueous sodium bicarbonate solution (3 × 50 ml.), washed with saturated aqueous sodium chloride solution (3 × 50 ml.), dried (Na₂ SO₄) and filtered. The filtrate was acidified with a 10% solution of anhydrous hydrogen chloride in dioxane (5 ml.) and then evaporated in vacuo to an oil. The oil was crystallized from warm 1,2-dimethoxyethane [850 mg., 77% yield, R_(f) 0.30 (4:1, benzene:ethanol on silicic acid), m.p.-forms a gel at 78° C.].

EXAMPLES 21-27

In like manner to that described in Example 20 the following compounds were prepared by using appropriate reactants (H₂ N-R₃) in place of cyclopentylamine: ##STR22##

    __________________________________________________________________________     Example         Reaction                                                                             Yield                                                                              Crystallization                                      Number                                                                              R.sub.3    Time (hrs.)                                                                          (%) Solvent System.sup.a                                                                   M.P. (° C)                                                                    R.sub.f.sup.b                          __________________________________________________________________________     21                                                                                             48    28  DME     172-176                                                                              .75                                    22                                                                                   ##STR23## 1.5   88  DME     154-157                                                                              .37                                    23   N(CH.sub.3).sub.2                                                                         16    23  DME/CH.sub.3 CN                                                                        82.sup.d                                                                             .38                                    24   CH.sub.2 CHCH.sub.2                                                                       16    77  DME/CH.sub.3 CN                                                                        70.sup.d                                                                             .29                                    25   CH(CH.sub.3).sub.2                                                                        48    55  DME     95.sup.d                                                                             .30                                    26   CH.sub.2 CH.sub.3.sup.c                                                                   72    84  DME     91.sup.d                                                                             .22                                    27   CH.sub.3.sup.c                                                                            72    90  DME     106.sup.d                                                                            .18                                    __________________________________________________________________________     .sup.a - DME .tbd.  1,2-dimethoxyethane; CH.sub.3 CN .tbd.  acetonitrile       .sup.b - 4:1, benzene:ethanol on silicic acid                                  .sup.c - ethylamine (methylamine)bubbled as a gas into                           acetic acid:chloroform solution                                              .sup.d - forms a gel                                                      

EXAMPLE 28 m-[N,N-Di(n-hexadecyl)aminomethyl]-N-(2,2,2-trifluoroethyl)-benzamidine

Ethyl-m-[N,N-di(n-hexadecyl)aminomethyl]-thiobenzimidate dihydrochloride (1.074 g., 1.5 mmoles) was added to a slurry of 2,2,2-trifluoroethylamine hydrochloride (406 mg., 3.0 mmoles) and anhydrous sodium acetate (246 mg., 3.0 mmoles) in chloroform (10 ml.) and glacial acetic acid (0.3 ml., 5.3 mmoles). The mixture was held for 12 hours at room temperature. It was then diluted to 300 ml. with chloroform, washed with saturated aqueous sodium bicarbonate solution (2 × 50 ml.), washed with saturated aqueous sodium chloride solution (2 × 50 ml.), dried (Na₂ SO₄) and filtered. The filtrate was acidified with a 10% solution of anhydrous hydrogen chloride in dioxane (5 ml.) and then evaporated in vacuo to a foam. The foam was recrystallized from 1,2-dimethoxyethane [974 mg., 86% yield, R_(f) 0.39 (4:1, benzene:ethanol on silicic acid), m.p.-forms a gel at 125°-127° C.].

EXAMPLES 29-33

In like manner to that described in Example 28 the following compounds were prepared by using appropriate reactants (H₂ N-R₃ ·HCl) in place of 2,2,2-trifluoroethylamine hydrochloride: ##STR24##

    __________________________________________________________________________     Example         Reaction                                                                             Yield                                                                              Crystallization                                      Number                                                                              R.sub.3    Time (hrs.)                                                                          (%) Solvent System.sup.a                                                                   M.P. (° C)                                                                    R.sub.f.sup.b                          __________________________________________________________________________     29                                                                                             24    57  DME     77-79.sup.c                                                                          .43                                    30                                                                                   ##STR25## 48    60  DME/CH.sub.3 CN                                                                        115-118.sup.c                                                                        .46                                    31                                                                                   ##STR26## 16    29  DME     238.sup.c                                                                            .60                                    32                                                                                   ##STR27##  3    55  DME/CHCl.sub.3                                                                         163-166                                                                              .00                                    33                                                                                   ##STR28## 24    40  DME/water                                                                              140.sup.c                                                                            .27                                    __________________________________________________________________________     .sup.a - DME .tbd.  1,2-dimethoxyethane; CH.sub.3 CN .tbd.  acetonitrile;      CHCl.sub.3 .tbd.   chloroform                                                  .sup.b - 4:1, benzene:ethanol on silicic acid                                  .sup.c - forms a gel                                                      

EXAMPLES 34-35

In like manner to that described in Examples 3-4 the following compounds may be prepared by using appropriate reactants in place of 3-hydroxy-1-propanesulfonic acid-γ-sultone:

    ______________________________________                                          ##STR29##                                                                     Example                                                                        Number     R.sub.3       Reactant                                              ______________________________________                                         34         CH.sub.2 SO.sub.3 H                                                                          iodosulfonic acid                                     35         (CH.sub.2).sub.6 SO.sub.3 H                                                                  6-hydroxy-1-hexanesulfonic                                                     acid-ζ-sultone                                   ______________________________________                                    

EXAMPLES 36-74

In like manner to that described in Examples 6-19 the following compounds may be prepared by using appropriate reactants (H₂ N-R₃) in place of p-anisidine: ##STR30##

    ______________________________________                                         Example                                                                        Number           R.sub.5                                                       ______________________________________                                         36               2-fluoro                                                      37               3-fluoro                                                      38               2-chloro                                                      39               3-chloro                                                      40               2-bromo                                                       41               3-bromo                                                       42               4-bromo                                                       43               2-hydroxyl                                                    44               3-hydroxyl                                                    45               2-nitro                                                       46               4-nitro                                                       47               2-trifluoromethyl                                             48               3-trifluoromethyl                                             49               4-trifluoromethyl                                             50               2-methyl                                                      51               3-methyl                                                      52               2-n-propyl                                                    53               3-ethyl                                                       54               4-isopropyl                                                   55               2-methoxy                                                     56               3-methoxy                                                     57               2-n-propyloxy                                                 58               3-ethoxy                                                      59               4-isopropyloxy                                                60               2-dimethylamino                                               61               3-dimethylamino                                               62               2-SO.sub.2 NH.sub.2                                           63               3-SO.sub.2 NH.sub.2                                           64               2-(CO)OCH.sub.3                                               65               3-(CO)OCH.sub.3                                               66               4-(CO)OCH.sub.3                                               67               2-(CO)O(CH.sub.2).sub.2 CH.sub.3                              68               3-(CO)OCH.sub.2 CH.sub.3                                      69               4-(CO)OCH(CH.sub.3).sub.2                                     70               2-SO.sub.2 CH.sub.3                                           71               3-SO.sub.2 CH.sub.3                                           72               2-SO.sub.2 CH(CH.sub.3).sub.2                                 73               3-SO.sub.2 (CH.sub.2).sub.2 CH.sub.3                          74               4-SO.sub.2 CH.sub.2 CH.sub.3                                  ______________________________________                                    

EXAMPLES 75-92

In like manner to that described in Examples 6-19 the following compounds may be prepared by using appropriate reactants (H₂ N-R₃) in place of p-ansidine:

    ______________________________________                                          ##STR31##                                                                     Example                                                                        Number   R.sub.6         R.sub.7                                               ______________________________________                                         75       chloro          methyl                                                76       trifluoromethyl methoxy                                               77       bromo           dimethylamino                                         78       chloro          dimethylamino                                         79       methyl          methyl                                                80       methyl          methoxy                                               81       2-propyl        dimethylamino                                         82       methoxy         dimethylamino                                         83       1-propyloxy     SO.sub.2 (CH.sub.2).sub.2 CH.sub.3                    84       ethyl           SO.sub.2 NH.sub.2                                     85       ethoxy          (CO)OCH(CH.sub.3).sub.2                               86       1-propyl        (CO)OCH.sub.3                                         87       dimethylamino   dimethylamino                                         88       2-propyloxy     dimethylamino                                         89       dimethylamino   SO.sub.2 NH.sub.2                                     90       dimethylamino   SO.sub.2 CH.sub.3                                     91       dimethylamino   (CO)OCH.sub.3                                         92       dimethylamino   (CO)O(CH.sub.2).sub.2 CH.sub.3                        ______________________________________                                    

examples 93-98

in like manner to that described in Examples 20-27 the following compounds may be prepared by using appropriate reactants (H₂ N-R₃) in place of cyclopentylamine:

    ______________________________________                                          ##STR32##                                                                     Example                                                                        Number               R.sub.3                                                   ______________________________________                                         93                   n-hexyl                                                   94                   2-butenyl                                                 95                   2-hexenyl                                                 96                   cyclopropyl                                               97                   cyclooctyl                                                98                   phenyl (1-propyl)                                         ______________________________________                                    

EXAMPLE 99-103

In like manner to that described in Examples 28-33 the following compounds may be prepared by using appropriate reactants (H₂ NR₃.HCl) in place of 2,2,2-trifluoroethylamine hydrochloride:

    ______________________________________                                          ##STR33##                                                                     Example                                                                        Number             R.sub.3                                                     ______________________________________                                          99                (CH.sub.2).sub.2 OH                                         100                (CH.sub.2).sub.7 OH                                         101                (CH.sub.2).sub.6 CF.sub.3                                   102                                                                                                ##STR34##                                                  103                                                                                                ##STR35##                                             

EXAMPLES 104-112

In like manner to that described in Examples 28-33 the following compounds may be prepared by using appropriate reactants (H₂ NR₃.HCl) in place of 2,2,2-trifluoroethylamine hydrochloride:

    ______________________________________                                          ##STR36##                                                                     Example                                                                        Number     R.sub.6       R.sub.7                                               ______________________________________                                         104        hydroxyl      chloro                                                105        hydroxyl      methoxy                                               106        hydroxyl      dimethylamino                                         107        hydroxyl      SO.sub.2 NH.sub.2                                     108        hydroxyl      (CO)OCH.sub.3                                         109        hydroxyl      N(CH.sub.3).sub.3.sup.+ Cl.sup.-                      110        N(CH.sub.3).sub.3.sup.+ Cl.sup.-                                                             methyl                                                111        N(CH.sub.3).sub.3.sup.+ Cl.sup.-                                                             dimethylamino                                         112        hydroxyl      ethyl                                                 ______________________________________                                    

EXAMPLE 113 Antiviral Activity of m-[N,N-di(n-hexadecyl)aminomethyl]-N-allylbenzamidine Dihydrochloride

Three groups of ten female albino mice (20-25 g. body weight) were given single 0.5 ml. intraperitoneal injections containing dosage levels of 1.5, 5, and 15 mg. of the named compound/kg. body weight, respectively. A fourth control group was given no such injection. Eighteen to twenty-four hours later all four groups were challenged with a 0.2 ml. subcutaneous injection containing 20-30 times the LD₅₀, the dosage level causing a 50% death rate in ten days, of encephalomyocarditis (EMC) virus. The following survival data were recorded for the following ten days:

    ______________________________________                                         Dosage Level                                                                   of Named Number of Survivors on Day Number                                     Compound 0     1     2   3   4   5   6       8   9   10                                                     S.sub.r                                           ______________________________________                                         15 mg./kg.                                                                              10    10    10  10   9  8   8   8   8   8   8                                                      80                                                                             5 10 10 10 10 10 6 6 6 5 5 5 53                                                1.5 10 10 10 10  9 5 4 2 2 2 1 19                                              0 (control) 10 10 10  9  3 1 1 0 0 0 0 --         ______________________________________                                                                      3                                            

Antiviral activity is expressed as the relative survival (S_(r)) in experimental groups compared to the controls on the tenth day after challenge. S_(r) is defined by the formula ##EQU1## wherein S_(r) = relative survival

S_(x) = percent survival after ten days in experimental group

x_(i) = number of survivors on the ith day in experimental group

e_(i) = number of survivors on the ith day in control group The ED₅₀ [dosage level (mg. of compound/kg. body weight) required to obtain a fifty percent survival rate] is determined graphically by plotting S_(r) (ordinate) vs. ln dosage level (abscissa) and then fitting the points with a line of predetermined slope by least squares. The dosage level at which this fitted line has an ordinate of 50 is equivalent to the ED₅₀.

This graphical method was used to determine an ED₅₀ for the named compound of 4.7 mg. (as dihydrochloride salt)/kg.

EXAMPLES 114-143

In like manner to that described in Example 113 the antiviral activity was determined for the compounds listed below.

    ______________________________________                                         Example  Compound Prepared in                                                  Number   Example Number    ED.sub.50 (mg./kg.).sup.a                           ______________________________________                                         114      2                 4.7                                                 115      3                 8.0                                                 116      4                 9.9                                                 117      6                 5.3                                                 118      7                 12.3                                                119      8                 16.0                                                120      9                 7.7                                                 121      10                49.3                                                122      11                35.7                                                123      12                4.9                                                 124      13                21.6                                                125      14                8.0                                                 126      15                38.0                                                127      16                7.0                                                 128      17                12.9                                                129      18                17.9                                                130      19                8.9                                                 131      20                27.3                                                132      21                47.5                                                133      22                7.8                                                 134      23                5.0                                                 135      25                2.8                                                 136      26                7.6                                                 137      27                5.7                                                 138      28                3.8                                                 139      29                6.9                                                 140      30                7.7                                                 141      31                11.7                                                142      32                7.4                                                 143      33                37.2                                                ______________________________________                                          .sup.a all as mg. dihydrochloride salt except for Example 115 (mg. free        base)                                                                    

EXAMPLE 144 Ability of m-[N,N-di(n-hexadecyl)aminomethyl]-N-(p-hydroxyphenyl)-benzamidine to Induce Circulating Interferon

A quantity of the named compound was fused with equal weights of polysorbate 80 and glycerol. The mixture was then homogenized in hot 0.14 M NaCl containing 0.01 sodium phosphate, pH 7 (PBS). The resulting oil-in-water emulsion was readily diluted with PBS.

Female Swiss mice (20-25 g. body weight) were injected (intraperitoneal) with an amount of the above diluted emulsion containing 25 mg. of the named compound/kg. body weight. Eight, twelve, sixteen and twenty hours after injection samples of plasma were withdrawn from the mice. These samples were then serially diluted. L-929 mouse fibroblasts were incubated on microtiter plates with aliquots of the various samples of serially diluted plasma for eighteen hours at 37° C. The fibroblast monolayers were then washed with protein-free medium and challenged with 10-40 times the TCID₅₀, the dose in which 50% of the cultures are infected, of vesicular stomatitis virus (VSV). The virus was allowed to absorb for one hour at 37° C. before addition of 0.2 ml. of maintenance medium. The cultures were scored and analyzed about twenty-four to forty-eight hours later and the plasma interferon level, the reciprocal of the plasma dilution at which fifty percent of the cultures are protected, determined. The following data were obtained.

    ______________________________________                                         Plasma Interferon Levels (units/ml.)                                           Time (hrs.) after Injection                                                    8         12          16          20                                           ______________________________________                                         102       276         143         76                                           ______________________________________                                    

EXAMPLES 145-150

In like manner to that described in Example 144 the ability to induce circulating interferon was determined for the compounds listed below.

    ______________________________________                                                               Plasma                                                                         Interferon Levels (units/ml.)                            Example                                                                               Compound Prepared                                                                             Time (hrs.) after Injection                              Number in Example Number                                                                             8       12    16    20                                   ______________________________________                                         145    2              76      116   56    48                                   146    24             26      60    110   102                                  147    25             <17     114   34    154                                  148    27             37      95    100   71                                   149    28             38      160   126   49                                   150    30             66      87    61    64                                   ______________________________________                                    

EXAMPLE 151

Compounds wherein R₁ and R₂ are not both n-(hexadecyl) and/or the phenyl ring of formula I is not meta-substituted may be prepared in like manner as described in Examples 1-33 for the corresponding m-[N,N-di(n-hexadecyl)] compounds by using the appropriate starting materials, and tested for antiviral activity in like manner as described in Example 113. 

What is claimed is:
 1. A compound of the structure ##STR37## and the non-toxic acid addition salts thereof wherein R₁ and R₂ are each alkyl of from twelve to twenty-four carbon atoms; andR₃ is selected from the group consisting of --(CH₂)_(n) CH₂ OH, --(ch₂)_(n) -SO₃ H,and --(CH₂)_(n) CF₃,wherein n is an integer of from one to six.
 2. A compound of claim 1 wherein R₁ and R₂ are normal alkyl.
 3. A compound of claim 2 wherein R₁ and R₂ have an equal number of carbon atoms.
 4. A compound of claim 1 wherein R₁ and R₂ are n-hexadecyl.
 5. A compound of claim 1 wherein R₁ and R₂ are n-octadecyl.
 6. A compound of claim 1 wherein the benzene ring of said structure is meta substituted.
 7. A compound of claim 1 wherein R₁ and R₂ are n-hexadecyl and the benzene ring of said structure is meta substituted.
 8. A compound of claim 1 wherein R₃ is selected from the group consisting of --(CH₂)_(n) -SO₃ H and --(CH₂)_(n) CF₃, wherein n is an integer of from one to three.
 9. A compound of claim 7 wherein R₃ is 2,2,2-trifluoroethyl. 